Self-tailing portable capstan

ABSTRACT

A self-tailing capstan for use in pulling and/or hoisting heavy loads or for tensioning lines, etc., includes a frame upon which first and second drums are rotatably mounted with their axes parallel. The first drum is rotatable in only one direction with reverse rotation being prevented typically by a ratchet and pawl assembly, while the second drum is freely rotatable in either direction. A detachable turning means such as a lever is provided the preferred embodiment of the invention to turn either drum as desired. In operation of the preferred embodiment, a flexible line is wrapped at least once around each drum. The length of line winding onto the two drums during hauling is defined as the &#39;&#39;&#39;&#39;leading segment,&#39;&#39;&#39;&#39; and the length of line unwinding from the second drum is defined as the &#39;&#39;&#39;&#39;tailing segment.&#39;&#39;&#39;&#39; The tailing segment always passes through a block attached either to the load or to a fixed anchor. The leading end of the line is attached to either the load or the anchor, except when the frame itself is anchored, in which case the leading end passes through a block and then is attached to a block or blocks through which one or more parts of the tailing segment is passed. The frictional grasp of the line wraps around the second drum is greater than that of the wraps around the first drum so that reverse rotation of the second drum may release line tension or lower the load without disengagement of the first drum&#39;&#39;s ratchet and pawl assembly. In a modified form of the invention, a differential driving assembly is provided to rotate the two drums simultaneously but at different circumferential speeds. The modified form of the invention may be employed with an endless line reeving to achieve an extremely high mechanical advantage.

United States Patent Kinnicutt, Jr.

[54] SELF-TAILING PORTABLE CAPSTAN Roger Klnnicutt, Jr., 50 Berwick St., Worcester, Mass. 01602 [22] Filed: March 13,1970

[21] AppI.No.: 19,432

[72] Inventor:

[s2 U.S. Cl ..254/l83,254/l50, 74/412 51 na. c1 ..B66dl/26 [58] FieldolSearch.........................254/l83,185,190,I50;

Primary Examiner-Evon C. Blunk Assistant Examiner-Merle F. Matfei Attorney-Chittick, Pfund, Birch, Samuels 8: Gauthier [57] ABSTRACT A self-tailing capstan for use in pulling and/or hoisting heavy loads or for tensioning lines, etc., includes a frame upon which [45] July 18, 1972 first and second drums are rotatably mounted with their axes parallel. The first drum is rotatable in only one direction with reverse rotation being prevented typically by a ratchet and pawl assembly, while the second drum is freely rotatable in either direction. A detachable turning means such as a lever is provided the preferred embodiment of the invention to turn either drum as desired. in operation of the preferred embodiment, a flexible line is wrapped at least once around each drum. The length of line winding onto the two drums during hauling is defined as the leading segment, and the length of line unwinding from the second drum is defined as the tailing segment." The tailing segment always passes through a block attached either to the load or to a fixed anchor. The leading end of the line is attached to either the load or the anchor, except when the frame itself is anchored, in which case the leading end passes through a block and then is attached to a block or blocks through which one or more parts of the tailing segment is passed. The frictional grasp of the line wraps around the second drum is greater than that of the wraps around the first drum so that reverse rotation of the second drum may release line tension or lower the load without disengagement of the first drums ratchet and pawl assembly.

in a modified form of the invention, a differential driving assembly is provided to rotate the two drums simultaneously but at different circumferential speeds. The modified form of the invention may be employed with an endless line reeving to achieve an extremely high mechanical advantage.

3 Claims, 15 Drawing Figures Patented July 18, 1972 3,677,521

6 Sheets-Sheet 1 I NVEN TOR.

ROGER KINNICUTT,JR. W Fwd 6W4.

L/KOHTML ATTORNEYS 6 swam-sh 3 Pat ROGER KINN|CUTT'JR BYCILQM. 6 W; ML

ATTORNEYS Patented July 18, 1972 6 Sheets-Sheet 5 mvsmox.

ROGER KINNICUTT,JR. BY Clufl l, p qmz BWL MMAM ATTORNEYS Patented July 18, 1972 6 Shoots-Sheet 4 INVENTOR.

ROGER KmmcuT'r ATTORNEYS Patented July 18, 1972 3,677,521

6 Sheets-Sheet a liliilih 1N VENTOR.

ROGER KINNICUT T, JR.

BY PM swig W g 1W ATTORNEYS 6 Sheets-Sheet 6 INVENTOR.

ROGER KINNICUTT BYWI 9W5 MA/(LIL M ATTORNEYS Patented July 18, 1972 SELF-TAILING PORTABLE CAPSTAN BACKGROUND OF THE INVENTION This invention relates generally to manually operable hoisting, tensioning and hauling devices, and is particularly concerned with a portable self-tailing capstan assembly.

There are presently two basic types of prior art devices available for manually pulling or hoisting loads by means of drums and levers in association with lines and pulleys. One such device comprises a lever operated winch which accumulates a flexible line on a drum as the load is moved. A number of problems are associated with this type of arrangement. For example, the width and diameter of the winch drum and the diameter of the line employed present an inherent limitation on the total length of line that can be accumulated on any particular winch. This in turn limits the distance that the load can be moved by the winch. To compensate for this deficiency, winches are sometimes provided with larger diameter drums and/or high flanges on the dnim in an attempt at increasing the line storage capacity of the device. However, it should be noted that since the mechanical advantage of a winch is proportional to the ratio of the lever radius to the drum radius, the accumulation of line on the drum progressively increases the effective drum radius and thus progressively decreases the mechanical advantage of the device. Also, as successive layers of line are wound tightly onto the drum, the underlying layers are subjected to crushing and abrasion, thereby resulting in in creased wear and premature failure of the line.

Another problem with winches lies in the fact that the entire pulling force is carried by a single line leading from the drum which is journalled for rotation between bearings in a stationary housing. As the line is wound laterally from one end of the drum to the other, the bearings are subjected to uneven loading and at times, one hearing or the other will carry nearly the full load. Also, since the winch is normally in a fixed position relative to the load, the drum shaft, ratchets and pawls are subjected to the full torque required to move the load. This in turn makes it necessary to employ heavy duty winch components capable of withstanding the high resulting stresses. Accordingly, winches capable of lifting or moving heavy loads are usually of necessity heavy, cumbersome and difficult to handle and transport.

Stationary capstans are also commonly employed to haul or lift loads. These devices have certain advantages over winches. For example, since the line is not accumulated on the capstan drum, the effective drum radius is not increased during the hauling or loading operation, and thus the mechanical advantage of the device is not impaired. Also, the distance that the load can be moved is not dependent on the line storage capacity of the device.

There are, however, a number of problems associated with such stationary capstan devices. For example, the line leaving the capstan drum must be tensioned or tailed to maintain sufficient friction between the capstan drum and line wrapped thereon. The tailing operation is usually performed manually and presents no particular problem where the capstan is being operated from a fixed base, such as the deck of a boat. However, where it is intended to have the capstan portable as in the present invention, a separate tailing operation is simply not feasible.

To stop heretofore known winches and capstan devices during hauling, a pawl must be engaged with ratchet teeth formed on the winding drum to statically stabilize and prevent reverse rotation of the drum while the reeving is tensioned. Such arrangements present significant safety hazards in that to release line tension or to allow the load to move away from the anchor as in lowering a scaffolding, the pawl must be released from the ratchet teeth. Unless precautions are taken while the pawl is so released to maintain sufficient force on the operating lever, the scaffold may inadvertently fall to the ground.

SUMMARY OF THE INVENTION In accordance with the present invention a portable, selftailing capstan assembly is provided with two drums rotatably mounted on an elongated, portable frame with their axes parallel to each other. The first capstan drum is allowed to rotate in only one direction, with reverse rotation being prevented typically by a ratchet and pawl assembly. The second capstan drum is mounted for unrestricted rotation in either direction. The preferred embodiment provides a lever or handle for turning and can be attached to either the first or second drum. The frame is also provided with means for securing one end ofa flexible line thereto.

In operation of this embodiment, one end of a flexible line of appropriate tensile strength is fastened to the frame and the other end inserted through a block secured to the load. The line is then wrapped at least once around each of the two drums and the other end secured to an anchor. The entire as sembly is then pulled toward the anchor until all line segments are tensioned.

Thereafter, the lever is rotated to begin pulling or lifting the load towards the anchor. Continued rotation of the capstan drums causes both the load and the capstan assembly to move towards the anchor. The maximum distance that the load may move towards the anchor is equal to the initial distance between the capstan assembly and anchor divided by the mechanical advantage achieved by the particular reeving an rangement being employed. It is important to note that since the line is not accumulated on either drum, the mechanical ad vantage of the capstan assembly remains constant and is limited only by the diameter of the drums plus line wraps as re lated to the length of the lever or handle plus the reeving employed. The tensioning of all line segments produces other significant advantages; more particularly, the tailing segment of the line, i.e., that portion of the line leaving the second drum in hauling, is always tensioned. The necessity to resort to a separate tailing operation is, therefore, completely obviated.

A more important advantage of the preferred embodiment, however, is that the tailing tension and the leading tension acting on the second drum are always equal, regardless of the mechanical advantage of the reeving employed. Thus, the second drum is maintained in a state of mechanical equilibrium so that the handle may be released without fear that the load will be released. This feature is particularly important when the device is used in raising and lowering scaffolding and the like.

Furthermore, when lowering the load by rotating the lever affixed to the second drum in the opposite direction, the ten sion in the line segment between the drums is only momentarily relieved. Since the first capstan drum is prevented from reverse rotation, the line will slip around that drum as long as the second drum is being rotated in the reverse direction. When such reverse rotation of second drum ceases, however, the tension will be restored and the entire apparatus will again come to equilibrium, thereby enabling the device to lower its load without releasing the rotation preventing means connected to the first drum.

A modified form of the invention provides a differential drive assembly for driving the two capstan drums at different surface speeds, which device may be employed with an endless loop of flexible line to haul very heavy loads at a high mechanical advantage. In this embodiment and its associated reeving, all line segments are again tensioned to insure selftailing operation. The high mechanical advantage inherent in the differential drive assembly significantly reduces the danger of the load being released during lowering since only a relatively small force need be applied to the lever to maintain equilibrium. In addition to its low speed, high advantage, mode of operating the modified embodiment may also be provided with means to afford the operator the option of high speed, low mechanical advantage operation for lighter loads.

It is, accordingly, a general object of the present invention to provide a portable self-tailing capstan assembly.

Another object of the invention is to provide a portable lifting, tensioning or hauling device that is lightweight, easy to handle and wherein the efficiency and inherent mechanical advantage of the device is not diminished or otherwise limited by an accumulation of line on the device itself.

A further object of the present invention is to provide a portable self-tailing capstan assembly which is self-aligning during normal operation.

It is yet another object of the invention to provide a portable, self-tailing lifting apparatus in which a load may be lowered without disengaging ratchets, pawls and the like.

A still further object of the invention is to provide a portable, self-tailing capstan device capable of operation in both low speed, high advantage and high speed, low advantage modes.

DETAILED DESCRIPTION These and other objects and advantages of the present invention will become more apparent as the description proceeds with the aid of the accompanying drawings wherein:

FIG. I is an end elevation of a capstan device according to the preferred embodiment of the invention:

FIG. 2 is a side elevation of the capstan device of FIG. I with a turning lever shown detachably mounted to one capstan drum;

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2',

FIGS. 4 and 5 are elevations of the preferred detachable turning lever for use in the preferred embodiment;

FIG. 6 is a fragmentary sectional view of the outer end of one of the drums showing the preferred construction for axial restraint of the rotatably mounted capstan drums;

FIG. 7 is a sectional view taken along line 7-7 of FIG. 6;

FIG. 8 is an end elevation similar to FIG. 1 showing a dif ferential drive assembly according to a modified form of the invention;

FIG. 9 is a partially sectional view taken generally along line 99 of FIG. 8 showing the interconnection between the differential drive assembly and the two capstan drums;

FIG. I0 is an elevation of a ratchet and pawl assembly interposed between the first capstan drum and its driven gear;

FIG. 11 is a sectional view taken along line 11-" in FIG. I0;

FIG. 12 is a schematic representation of the preferred embodiment shown connected between a load and an anchor by a typical reeving arrangement;

FIG. 13 is a schematic diagram depicting the preferred embodiment reeved for use as a stationary capstan; and

FIG. I4 is a schematic three-dimensional representation of the preferred embodiment in ascaffold reeving;

FIG. 15 schematically illustrates a typical endless line reev ing for the modified form of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS A capstan device according to the preferred embodiment of the invention is shown in FIGS. I through 7 and indicated generally by the reference numeral 10. The general features of the invention are best seen with reference to FIGS. 1, 2 and 3 wherein the capstan device 10 is shown comprising an elongated frame member 12 upon which a first capstan drum l4 and a second capstan drum 16 are rotatably mounted on spaced, parallel axis. The preferred mounting means for the capstan drums l4 and 16 is a C-shaped drum shaft bar 18 which is passed through and secured to the frame member 12 by conventional means to present two mounting shafts 20 and 20' for the capstan drums I4 and 16. The frame member 12 is preferably bent inwardly toward the capstan drums at its outer ends and is there provided with line receiving means such as apertures 22 and 24.

The drums I4 and I6 may be rotatably mounted on their respective shafts 20 and 20 in any conventional manner. From the standpoint of ease of assembly and minimizing construction costs, I prefer to employ a split thrust ring 26 at the outer ends of both drums l4 and I6 as seen typically in FIG. 6. The split thrust ring 26 is axially secured to the shaft 20 by a pair of flat slots 28 formed on opposite sides of the shaft 20, and is surrounded by an appropriate sleeve 30, which sleeve and thrust ring are confined within an enlarged diameter bore 32 formed in the outer end of the drum 14 by a cap 34 which is fastened directly to the outer end of the drum 14 by any conventional means such as grooved drive pins 36. It should be noted that the shafts 20 and 20' extend outwardly from the drums I4 and 16 and that the caps 34 are each provided with a keyed or hexagonal opening 38 to detachably receive the preferred turning lever to be later described.

With reference now to FIG. 3, I prefer to form the inner ends of both drums l4 and 16 with hexagonal hubs 40 and 40' respectively to simplify the assembly of the device. Rotation of the first capstan drum I4 is controlled by means of a pawl assembly generally indicated by the reference numeral 42 which assembly comprises a tooth ratchet wheel 44 mounted on the hexagonal hub 40 of the first drum 14 so as to be confined between the drum l4 and the frame I2 and to rotate in unison therewith. A cooperating pawl 46 is mounted in operative jux taposition to the ratchet wheel 44 on the inner surface of the frame 12 by pawl pin 48 and is urged into operative engage ment with the ratchet wheel 44 by a spring member 50 acting between the pawl and a shoulder 52 defined by the peripheral surface of a pawl assembly plate 54 secured to the inner side of the frame 12 by conventional means. The pawl assembly is enclosed by a pawl assembly cover plate 56 shown in FIG. I. and a pawl release pin 49 is also provided to release the assembly 42. The pawl assembly 42 functions to permit rotation of the first capstan drum 14 in only one allowed direction, and other conventional means, such as for example a one-way clutch, may be employed to perform this function without departing from my invention. Since the second capstan drum 16 is freely rotatable, a spacer plate 58 is merely mounted on its hexagonal hub 40' to be confined between the frame 12 and the drum 16.

The preferred detachable turning lever 60 is shown operatively mounted to the outer end of the first capstan drum 14 in FIG. 2. The details of the turning lever 60 are best seen in FIGS. 4 and 5 as including an elongated lever 62 having at one end a handle 64 extending perpendicularly outward therefrom. The other end of the lever is secured to an oppositely extending hexagonal key member 66 which has a keyed hexagonal periphery 68 adapted to be insertably received by the keyed openings 38 in the caps 34, which key member also has a bore 70 adapted to insertably receive the outer ends of the shafts 20 and 20'. It should thus be apparent that the outer ends of the shafts 20, 20' provide a pilot so that the handle may be detachably secured to each drum 14 or 16 to rotate either drum as desired.

Having thus described the preferred embodiment of the in' vention this discussion will now proceed to its operation. A typical and perhaps the simplest use of the capstan device 10 for lifting purposes is shown diagrammatically in FIG. 12 wherein the capstan device is shown positioned between a fixed overhead anchor 72 and a movable load 74. A block 76 is secured to the load 74 as by a hook 78. One end of a flexible line 80, such as a rope, is secured to the line receiving aperture 24 and the line segment 800 then passes through the block 76 from whence a "tailing segment" 80b passes back to the capstan device 10 where it is wound around the second capstan drum 16 one or more times. From the drum 16 another tailing line segment 800 extends to the first drum 14 where it is again wrapped at least once around that drum. The first drum leading line segment 80d is then secured to the anchor 72. The first or second drum 14 or 16 is then rotated in the clockwise direction (in the reeving shown) by turning the lever 60, which may be mounted to either drum during hauling, to tension all line segments 80 and thus place the capstan assembly 10 in readiness for operation. At this point it should be ap' parent that the tension thus exerted by the line segments 80a-d on the two drums l4 and I6 statically stabilizes the capstan device so that the frame 12 is disposed in substantially parallel relationship to the various line segments, thereby assuring that the axes of the two drums are normal to these line segments. This feature of the invention enables the capstan assembly 10 to move along the reeved line 80 during hauling without the necessity to employ auxiliary stabilizing means.

With the reeving arrangement shown in FIG. 12, the capstan 10 should be initially positioned near the load 74 with the line segments 80a and 80b as short as possible. As the lever 60 (preferably applied to the first druml4) is rotated in the clockwise direction, the leading segment" SM is wound onto the first capstan drum [4 while a corresponding amount of line passes from the capstan drum 14 as a "tailing segment 80c. At the same time, an identical length of line travels around the freely rotating second capstan drum, passes from the tailing segment 80c and enters the tailing segment 80b. It should be apparent that during such rotation, the tension in line segments 80a and 8% equals the load carried on line segment 80d divided by the mechanical advantage of the reeving (in this case 2). Since the second drum I6 is freely rotating, the tension in line segment 8% is transferred to line segment 80c to provide the tailing tension so that the first drum l4 acts as a capstan to lift the load 74.

The tension in the line segments 80b and 800 insures the development of adequate friction between the second drum l6 and the line wrapped thereon to provide a self-tailing action. Continued rotation of the drum [4 causes the distance a between the capstan device 10 and the anchor 72 to decrease at twice the rate that the distance b between load 74 and the anchor 76 decreases. The 2:] mechanical advantage provided by this particular reeving arrangement, coupled with the inherent mechanical advantage of the capstan assembly by virtue of the ratio of the length of the lever 60 to the radius of the drums provided an extremely efiicient lifting arrangement.

While it should be appreciated that hauling could also be accomplished by rotating the second drum 16 in a similar manner, I prefer to detachably mount the lever 60 to the first drum 14 for rotation in its allowed direction so that the operator may easily grasp the handle defined by the C-shaped exposed portion of the drum shaft and indicated at 18 (FIG. 2) with his non-turning hand to steady the device l0 during hauling. Moreover, the efficiency of the capstan device 10 is at the optimum when the lever 60 is engaged with the first drum during hauling, hoisting or tensioning.

When the load 74 has been lifted to its desired position, rotation of the lever 60 may be stopped at any point relative to the frame, and thereafter rotated in the reverse direction (if necessary) so that the pawl 46 engages the ratchet wheel 44. From an analysis of the forces acting on the capstan 10 at this point, it is seen that the tension in line segments 80a and 80!) again equals the overall load carried by segment 80d divided by the mechanical advantage of the reeving between the block 76 and the capstan l0, and the tailing tension in line segment 80b is transferred to line segment 80c over the freely rotatable second drum 16. The unequal tensions in line segments 80d and 80c cause the line to frictionally grasp the first drum 14 while the pawl assembly 42 bears the resulting unbalanced torque, whereby the load 74 is securely held in an elevated position. Thus the operator need only rotate the drum 14 until the load 74 is elevated to the desired height, reverse such rotation to insure positive engagement of the pawl assembly 42 (if necessary), and then release the lever 60. This holds true regardless of the reeving employed.

Once the load 74 has been raised, the lever 60 should be removed from the first drum l4 and secured to the second drum 16 so that the latter drum may be rotated in the non-allowed direction of the first drum.

In order to provide for lowering the load 74 without releasing the pawl assembly 42, the slippage resistance of the line wraps around the first drum 14 should be less than the slippage resistance of the line wraps around the second drum 16. One means for achieving this result is simply to wrap the line more times around the second drum 16 than around the first drum 14, say 3 wraps versus 2. Another way is to roughcn or otherwise increase the co-efficient of friction of the surface of the second drum 16 relative to that of the first drum [4, for example by knurling the surface of the second drum 16 as indicated at 82 in FIG. 2, while providing the first drum [4 with a smoother surface as indicated at 84. The choice of means employed to achieve this result will of course vary with the particular use to which the capstan assembly is put, with the only requirement being that the relaxation of the tension in segment 80c produced by reverse (counterclockwise) rotation of the second drum 16 must cause the line wraps around the first drum 14 to slip without causing the line wraps on the second drum 16 to also slip. The gripping action between the second drum l6 and its line wraps will thus positively control the position of the load as it is lowered. If rotation ofthe lever 60 ceases, the tension in line segment 80c will be immediately restored to cause the line to again grip the first drum 14 to bring the capstan assembly 10 back into equilibrium, thereby preventing a precipitous and uncontrolled fall of the load if the lever handle 64 is subsequently released.

A further and particularly useful employment of the invention is shown schematically in FIG. 14 wherein two capstan devices 10 are positioned at the ends of a vertically movable platform, such as a painters scaffold 86. In this reeving arrangement, which applies to both capstan devices, one end of a line 88 is fastened to the frame 12 through the lower line receiving aperture 24 with the line portion 88a passing down through a guide hole 90 in the platform 86 to a block 92 anchored to the ground or structure just beneath the lowest or starting point of the lift. The line portion 88b passes from the block 92 up through another guide hole 94, from whence it is serially wrapped at least once around each of the drums l6 and 14. The line portion 88d is then passed over a block 96 fixed to an overhead support 98 such as the eaves of a house, and back down to be secured to the platform as at 100.

With this arrangement, simultaneous rotation of the levers 60 raises both the capstan device 10 and the platform 86 at the same rate. Since the position of the capstan devices [0 relative to the platform 86 remain constant, the lifting devices are always accessible to operators riding on the platform 86 regardless of the elevation of the platform. Moreover, by passing the lines 88 through the guide holes 90 and 94, the platform is stabilized against horizontal sway.

The same relative movement between the capstan assembly and load will obtain with this reeving arrangement regardless of the load movement path relative to any plane, i.e., load and capstan move together horizontally, vertically or any slope between horizontal and vertical.

The lower the scafford 86, the second drums 16 may be reversely rotated to release tension in the line segment 88c whereby the line 88 will slip over the first drums 14 without disengaging the pawl assemblies 42. When the platform 86 has been lowered to to the desired height, rotation of the second drums 16 may be stopped to again tension line segment 88c, cause the first drums 14 to grip the line, and bring the capstan device back into equilibrium.

The only manual operation needed to raise or lower the device is thus merely the proper rotation of the drums l4 and 16. No further operations, such as engaging and disengaging pawls, must be performed to bring the device into equilibrium. In eliminating these further manual operating steps, the preferred embodiment of the present invention incorporates a safety feature which obviates the possibility of serious injuries to personnel who should neglect to re-engage pawls when the scaffolding is at a considerable height above the ground.

It is also possible to employ the capstan device 10 as a fixed hoist. An example of a reeving arrangement for such use is shown schematically in FIG. 13 wherein the frame 12 of the capstan 10 is secured to an anchor 102, say an overhead beam, as by coupling 104 passing through the upper line receiving aperture 22. One end of a hauling line 106 is fastened to the other line receiving aperture 24, passed downwardly to and around a floating pulley 108, from whence the tailing segment 106a passes to the capstan assembly 10 where it is wrapped around the drums 16 and 14 in the manner previously described. The leading line segment 106!) is then passed down to and around a block 110 secured to a load 112 and is then passed to and is secured to the floating pulley 108. This reeving provides a 4:1 mechanical advantage.

This description will now proceed to a modified form of the invention shown in FIGS. 8, 9, 10 and 11 and generally designated at 10. The modified capstan device 10' provides a differential drive assembly which mechanically interconnects the first and second drums l4, 16 to simultaneously drive both drums at different circumferential speeds. The preferred differential drive assembly, generally indicated at 114, includes three drive gears, all rotatably mounted in a conventional manner within a common housing 116, namely a first drum drive gear 118, a second drum drive gear 120, and a pinion drive gear 122 positioned between and meshed with both of the drum drive gears. The inner ends of the drum drive gears 118, 120 are provided with keyed or hexagonal hubs 124 and axial bores 126 similar to the hexagonal hub 68 and bore 70 of the turning lever 60 shown in FIGS. 4 and so that the driving assembly may be easily mounted to the basic capstan device by axially inserting the drive assembly along the exposed ends of the shafts until the hubs 124 are nested within the caps 34. Similarly, the outer end of the pinion gear 122 is formed to provide a hub 128 adapted to receive a conven tional turning means such as a lever having a complementary socket.

it should thus be apparent that when the pinion gear 122 is rotated in one direction, the drive gears 118 and 120 will rotate in the opposite direction to simultaneously drive their respective capstan drums 14, 16. Moreover, the first drum drive gear 118 has fewer gear teeth than does the second drum drive gear 120 so that the first capstan drum 14 rotates at a higher circumferential speed than the second capstan drum 16, assuming of course that the two drums have about the same diameter. There are of course other means which will be apparent to those skilled in the art for rotating the two capstan drums 14, 16 at different circumferential speeds, one alterna tive being to have the drive gears 118 and 120 with equal numbers of gear teeth while forming the first capstan drum 14 with a larger diameter than the second capstan drum 16. I prefer however to form thw two capstan drurns 14, 16 with substantially identical dimensions so as to reduce the manufacturing costs of the device, and to use the differential gear drive described to achieve differential surface speed.

A differential driving assembly 114 also provides a mechanical advantage in addition to that inherent in the reeving employed and that of the length of the handle used to turn the pinion gear 122 in relation to the effective radius of the drums 14, 16.

An alternate method for driving the first drum 14 only in its allowed direction by the first drum drive gear 118 is shown in FIGS. 10 and 11 as comprising a drive pawl 130 pivotally mounted to the outer end of the first drum cap 34 as by a pawl pin 132. A ratchet wheel 134 is formed on the inner end of the first drum drive gear 118 and the drive pawl 130 is urged into operative engagement therewith by a spring member 136 which is also secured to the first drum cap 34 by conventional fastening means 138. In this embodiment, the first drum drive gear 118 has a circular inner hub 140 which is adapted to be fully inserted through the opening 38 into the bore 30 formed in the outer end of the first capstan drum 14. When the first drum drive pawl assembly shown in FIG. 11 is compared to the pawl assembly 42 between the first drum 14 and the frame 12 shown in FIG. 3, it will be apparent when the first drum drive gear 118 is rotated in the allowed direction of the first drum (i.e. clockwise as shown), the engaged drive pawl 130 and ratchet wheel 134 will cause the first drum to rotate in its allowed direction. On the other hand, when the first drum drive gear 118 is driven in the non-allowed direction of the first drum, the pawl assembly 42 remains operative to prevent such reverse rotation of the first drum. This feature of the invention allows the operator of the capstan device 10' to select a low speedhigh mechanical advantage operating mode for the device, or on the other hand to select a high speed-low mechanical advantage mode of operation to the device. This feature will become more apparent from the following description of the modified form of the invention while in use.

A typical reeving arrangement for the modified form of the invention for lifting purposes is shown schematically in FIG. 15 wherein the capstan device 10' is shown positioned between a fixed overhead anchor 144 and a movable load 146. The capstan device 10' is reeved between the load 146 and the anchor 144 by an endless loop of flexible line 148 which is wrapped at least once around the second capstan drum 16, from which drum a line segment 148a passes up to and around a block 150 secured to the anchor 144 with a line segment 148b passing down to and is wrapped at least once around the first capstan drum 14 in the same direction of wrap as it is wrapped around the second capstan drum 16. A line portion 148C then passes downwardly for passage through a reeving arrangement between the capstan device 10' and the load 146 which has a higher mechanical advantage than the reeving between the capstan device 10' and the anchor 144. As shown, the load reeving includes a double load block and hook 152 and a pulley 154 which is secured to the frame 12 by conventional means such as a shaft 156 passing through the lower line receiving aperture 24. The line segment 148C passes down to and around one block of the double load block 152. up to and around the block 154, and then back down and around the other block of the double load block 152, from whence line segment 148d passes back to the second capstan drum 16. The line 148 may be spliced after such reeving has been accomplished, or the line 148 may be spliced as an endless loop with the differential drive assembly 114 removed from the capstan device 10' when conventional snatch blocks are used in the reeving. The line 148 should be wrapped around the second drum 16 so that the line segment 148a is located at its inner or frame end and so that line part 148d is located at the outer end, while the line segment 1481) should be located at the outer end of the first drum 14 and the line segment 1484' should be located at its inner end. This reeving arrangement stabilizes the device 10' against lateral sway during hauling by completely balancing the lateral torques applied to the device 10'.

The pinion gear 122 should then be rotated oppositely to the allowed direction of rotation for the first drum 14 so as to rotate both drums 14 and 16 in the allowed direction of the first drum 14 to tension all line segments 1480-d, thereby placing the capstan device 10' in readiness for operation. Since the differential drive assembly 114 rotates the first drum 14 at a higher circumferential speed than the second drum 16, continued rotation of the driving assembly 114 causes a greater length of line per rotation of the pinion gear 122 to pass over the first drum 14 from line segment 148b to line segment 148c than passes from line segment 1484 over the second capstan drum 16 to line segment 148a. Thus, more line is passed to the high mechanical advantage reeving between the capstan device 10' and the load 146 than is passing from the second drum 16 to the lower mechanical advantage reeving between the capstan device and the anchor 144, whereby the load and the capstan device 10 both move toward the anchor 144. The 4:1 mechanical advantage provided by this particular reeving arrangement, coupled with the mechanical advantage of the capstan device 10' by virtue of the ratio of the length of the lever used to rotate the pinion gear 122 to the radius of the drums l4 and 16, together with the inherent mechanical advantage of the differential drive assembly 114 provide a very high mechanical advantage which is particularly useful for manually lifting or hauling very large loads 146. To illustrate, a typical lever length is 7 '6 inches and a typical drum radius is 1 Yr inch, which combine to provide a mechanical advantage of 6 for the handle to drum radius ratio. Moreover, the mechanical advantage of the differential driv ing assembly 114 may be varied by varying the relative number of gear teeth for the first drum drive gear 118 and the second drum drive gear 120. If the first drum drive gear has 18 gear teeth, the pinion drive gear 122 has 20 gear teeth, and the second drum drive gear has 22 gear teeth, the differential drive assembly 114 is provided with a mechanical advantage of about whereby the total mechanical advantage achieved is about I20. To illustrate further, if the first drum drive gear 118 has 19 gear teeth, the pinion drive gear 122 has 20 gear teeth, and the second drum drive gear 120 has 21 teeth, the mechanical advantage of the differential drive assembly is increased to about l0 with an overall mechanical advantage of about 240. Of course, there are many other combinations of gears which may be employed in the differential drive assembly to further increase this mechanical advantage. From a commercial point of view, I prefer to use readily available gears so as not to prohibitively increase the cost of the device.

Since many revolutions of the pinion gear 122 are required to move the load 146 towards the anchor 144 while fully utiliz ing the mechanical advantage provided by the differential drive assembly 114, this mode ofoperation shall be referred to as low speed-high advantage hauling which is particularly useful in lifting extremely large loads. The modified capstan device 10' may also be provided with a high speed-low advantage mode of operation capability if a ratchet and pawl assembly such as shown in FIGS. 10 and 11 is interposed between the first drum drive gear 118 and the first drum 114. Such high speed-low advantage hauling may be accomplished by merely rotating the pinion gear 122 in the direction opposite to which it is rotated in the low speed-high advantage mode so as to rotate both drum drive gears 118, 120 in the direction opposite to the allowed direction of the first capstan drum 114. Since the pawl assembly 42 prevents reverse rotation of the first drum 14, the net result of such rotation will be that the second capstan drum 16 will be rotated in the reverse or counterclockwise direction as shown in FIG. 15 while the first capstan drum 14 remains stationary. The tension in line parts l48b and 148c insured that no line slips over the first drum 14, while reverse rotation of the second drum 16 causes an equal amount of line to pass from the line part 148a to line part 148d to decrease the length of line in the low mechanical advantage reeving between the capstan device 10' and the anchor 144 while increasing the length of line in the high mechanical advantage reeving between the capstan device 10 and the load 146 which results in movement of the load 146 toward the anchor 144. Thus the provision of a ratchet and pawl assembly or similar device for permitting rotation in only one direction interposed between the first drum drive gear 118 and the first drum 114 provides the modified form of the capstan device 10' with two modes of operation which may be selected by the operator merely by rotating the handle in one of two directions.

When the load 146 has been lifted to its desired position, it may be lowered by releasing the pawl assembly 42 as by depressing the pawl release pin 49 (FIGS. 2 and 3) against the spring member 50 to allow the differential driving assembly 114 to drive the two capstan drums in the non-allowed direction of the first drum 14 to pass more line from line segment 148cm line segment 1 18!: to over the first capstan drum 14 than passes from line segment 148a to line segment 148d over the second capstan drum 16 to lower in a low speed-high advantage manner. The high mechanical advantage afforded the device by the differential driving assembly 114 greatly mitigates the danger that the load will be precipitiously released since the operator need apply a relatively small force to the handle to maintain equilibrium.

In light of this description, it should be apparent that once again all line segments 148 are always tensioned so that no separate tailing operation is required to operate the capstan device 10. The elimination of a separate tailing operation together with an endless loop reeving 148 provides a concomrnitant advanta e in that less line is required to move a load a given distance. urthermore, this line IS never accumulated on any given drum and therefore is not subjected to crushing forces which can cause premature failure and the distance which the load may be moved by the capstan device is not limited by the dimensions of the drums. Additionally, since the capstan device is adapted to be portable and move along the reeved line during hauling, the components of the capstan device may be of lighter weight and less cumbersome than those employed in prior capstans and winches.

In view of the foreging, it should now be apparent that this invention provides advantages heretofore unavailable with known prior art devices. This is true regardless of the reeving arrangement employed.

It is my intention to cover all modifications and equivalents of the embodiments herein shown for disclosure which do not depart from the spirit and scope of the invention as defined by the appended claims.

lclaim:

1. For use in a reeving arrangement employed to pull a movable load towards a fixed support, the said reeving arrangement including a flexible elongated tensioning member such as for example a rope or cable and at least one pulley block attached to the load, a portable capstan device comprising in combination: a frame assembly including a first U- shaped frame member forming laterally spaced parallel shafts joined by a base element, said shafts being additionally joined at locations spaced inwardly from the distal ends thereof by a second frame member which is spaced laterally from said base element; capstan drums rotatably mounted on each of said shafts; means cooperatively associated with said frame assembly and one of said capstan drums for permitting rotation of said one drum in one direction and for preventing rotation of said one drum in the opposite direction; the other of said drums being rotatable in either direction independently of said one drum; and operating means for rotating one or the other of said capstan drums in said one direction, the said flexible elongated tensioning member being attached at one end to said frame assembly, passed through said pulley block, wound at least once around each of said capstan drums and then attached at the other end to said fixed support, whereby rotation of the drums in said one direction will cause said load to be pulled towards said fixed support.

2. The apparatus as claimed in claim 1 further characterized by said means cooperatively associated with said frame assembly one of said capstan drums comprising ratchet teeth on said one drum, and a pawl carried by said frame assembly, said pawl being urged into cooperative engagement with said ratchet teeth by spring means.

3. The apparatus as claimed in claim 1 further characterized by said operating means being comprised of a handle adapted for removable engagement with either of said drums.

UNITED STA'IES PA'llCNT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 677 S21 D t d July 18 1972 Inventor(s) Roger lnnlcutt Jr It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 10 line 56 before "one" insert and Signed and sealed this 15th day of May 1973 (SEAL) Attest:

EDWARD M. FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM PO-iOSO (10-69) USCOMM-DC wan-poo ".5. GOVERNMENT PRINTING OFFICE I969 O366-33l. 

1. For use in a reeving arrangement employed to pull a movable load towards a fixed support, the said reeving arrangement including a flexible elongated tensioning member such as for example a rope or cable and at least one pulley block attached to the load, a portable capstan device comprising in combination: a frame assembly including a first U-shaped frame member forming laterally spaced parallel shafts joined by a base element, said shafts being additionally joined at locations spaced inwardly from the distal ends thereof by a second frame member which is spaced laterally from said base element; capstan drums rotatably mounted on each of said shafts; means cooperatively associated with said frame assembly and one of said capstan drums for permitting rotation of said one drum in one direction and for preventing rotation of said one drum in the opposite direction; the other of said drums being rotatable in either direction independently of said one drum; and operating means for rotating one or the other of said capstan drums in said one direction, the said flexible elongated tensioning member being attached at one end to said frame assembly, passed through said pulley block, wound at least once around each of said capstan drums and then attached at the other end to said fixed support, whereby rotation of the drums in said one direction will cause said load to be pulled towards said fixed support.
 2. The apparatus as claimed in claim 1 further characterized by said means cooperatively associated with said frame assembly one of said capstan drums comprising ratchet teeth on said one drum, and a pawl carried by said frame assembly, said pawl being urged into cooperative engagement with said ratchet teeth by spring means.
 3. The apparatus as claimed in claim 1 further characterized by said operating means being comprised of a handle adapted for removable engagement with either of said drums. 